The Claassen board of inquiry, instituted by President Jacob Zuma, has found that suspended national police commissioner Riah Phiyega is not fit to hold office, Business Day reported.
The inquiry's report was made public for the first time this week after being declassified by the portfolio committee on police, the report stated.
The inquiry followed recommendations by the Farlam Commission of Inquiry, investigating the 2012 Marikana massacre, that a probe should be conducted into Phiyega's fitness to hold office for her conduct during the massacre as well as her conduct as a witness at the commission.
Phiyega is challenging the report's findings in court.
Phiyega's lawyer, Sandile July, told Business Day that the report was "problematic".
He reportedly said that the Claassen inquiry's findings contradicted the Farlam commission's findings "without any evidence to support the changes".
The Claassen report reportedly found Phiyega guilty of "serious misconduct" who "provided vague responses to questions about the tactical option the police had devised to handle the scene where mineworkers had congregated during the strike," Business Day reported.
The paper said Zuma had received the report in mid-December but has not indicated how he will implement its recommendations.
The report says Phiyega breached her duties in controlling the police's response to the strike which preceded the police opening fire on the miners.
It said she tried to avoid taking responsibility for implementing the tactical option. This had "tainted her evidence to the extent that her credibility is in serious doubt", Business Day quoted the report as saying.